Deep-sea record of impact apparently unrelated to mass extinction in the Late Triassic.

Title	Deep-sea record of impact apparently unrelated to mass extinction in the Late Triassic.
Authors	N Shirai, Xin Toh, Honami Sato, Y Hatsukawa, T Osawa, Paulo H. N. Harada, Munetomo Nedachi, Tetsuji Onoue, Tomoki Nakamura, Paul Orchard, M Koizumi, Yoshihiro Hidaka, M. Ebihara, T Noguchi
Magazine	Proceedings of the National Academy of Sciences of the United Kingdom
Date	11/20/2012
DOI	10.1073/pnas.1209486109
Introduction	The 34-million-year interval of the Late Triassic is characterised by the formation of several large impact structures on Earth. While these impact events have been considered potential contributors to biotic extinction events, particularly the end-Triassic extinction event, this hypothesis remains debated due to the lack of stratigraphic records of ejecta deposits. This study presents evidence of an impact event, indicated by anomalies in platinum group elements, nickel-rich magnetite, and microspherules, from the middle Norian (Upper Triassic) deep-sea sediment in Japan. The presence of high iridium concentrations, up to 41.5 parts per billion, in the ejecta deposit suggests that iridium-enriched layers may have a global distribution during the Late Triassic. The ejecta deposit is associated with microfossils correlating with the 215.5-Mya, 100-km-wide Manicouagan impact crater in Canada. Radiolarian analysis reveals no significant biotic extinction across the impact event horizon, nor any faunal turnover in other marine planktons. However, evidence of such events has been observed among marine faunas and terrestrial tetrapods in North America, suggesting the Manicouagan impact may have affected terrestrial and marine life near the impact site, but not in pelagic marine environments.
Quote	N Shirai, Xin Y Toh and Honami Sato et al. Deep-sea record of impact apparently unrelated to mass extinction in the Late Triassic. 2012. DOI: 10.1073/pnas.1209486109
Element	Iridium (Ir) , Nickel (Ni) , Platinum (Pt)